function every(collection, pre) {
    for (let i = 0; i < collection.length; i++)
        if (!collection[i][pre])
            return false;
    return true;
}

every([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}, {
    "user": "Laa-Laa",
    "sex": "female"
}, {"user": "Po", "sex": "female"}], "sex");

